1. Field of the Invention
The present invention relates to ionically conductive polymeric materials, to their preparation and to their use as a solid electrolyte.
2. Discussion of the Background
Metal salts MX.sub.n, in which M denotes a metal cation and X denotes a monovalent anion, form complexes with some solvating polymers, in particular those incorporating sequences of polyether type (for example poly(ethylene oxide) PEO, poly(propylene oxide) PPO, poly(bis-.omega.-methoxy-oligooxyethylene-phosphazene) ME.sub.n P) or polyamines (PEI). These materials have, in a determined range of temperature and salt concentration, an ionic conduction which can be employed for the production of electrochemical systems, in particular storage batteries (European Patent No. 13,199).
The ionic conductivity of these complexes depends on the degree of dissociation of the salt MX.sub.n and the highest values for a given species M are obtained with anions X.sup.- in which the negative charge is delocalized and which do not have any complexing character. However, the mobility of the cations M.sup.n+ in this macromolecular medium depends on the rate of exchange in the ligands incorporated in the macromolecular framework in the form of solvating units around these cations. In the case of n&gt;1 and/or in the case of the transition elements, these kinetics are slow and generally entail low or zero values of the cation transport number in these materials. In particular it is therefore difficult to perform electrochemical reactions involving a reversible contribution of the species M.sup.n+ to the electrode (metal deposition-dissolution, insertion, etc).